Memory Performance - Not Very Nehalem

Let’s start at the obvious place, memory performance. Nehalem moved the memory controller on-die, but Clarkdale pushes it off again and over to an on-package 45nm graphics core.

To make matters worse, the on-package chipset is a derivative of the P45 lineage. It’s optimized for FSB architectures, not the QPI that connects the chipset to Clarkdale. Let’s look at the numbers first:

Processor L1 Latency L2 Latency L3 Latency
Intel Core i7-975 4 clocks 10 clocks 34 clocks
Intel Core i5-750 4 clocks 10 clocks 34 clocks
Intel Core i5-661 4 clocks 10 clocks 39 clocks
AMD Phenom II X4 965 3 clocks 15 clocks 57 clocks
Intel Core 2 Duo E8600 3 clocks 15 clocks  

 

L1 and L2 cache latency is unchanged. Nehalem uses a 4-cycle L1 and a 10-cycle L2, and that’s exactly what we get with Clarkdale. L3 cache is a bit slower than the Core i7 975, which makes sense because the Core i5 661 has a lower un-core clock (2.40GHz vs. 2.66GHz for the high end Core i7s) Intel says that all Clarkdale Core i5s use the same 2.40GHz uncore clock, while the i3s run it at 2.13GHz and the Clarkdale Pentiums run it at 2.0GHz.

Processor Memory Latency Read Bandwidth Write Bandwidth Copy Bandwidth
Intel Core i7-975 45.5 ns 14379 MB/s 15424 MB/s 16291 MB/s
Intel Core i5-750 51.5 ns 15559 MB/s 12432 MB/s 15200 MB/s
Intel Core i5-661 76.4 ns 9796 MB/s 7599 MB/s 9354 MB/s
AMD Phenom II X4 965 52.3 ns 8425 MB/s 6811 MB/s 10145 MB/s
Intel Core 2 Duo E8600 68.6 ns 7975 MB/s 7062 MB/s 7291 MB/s

 

Here’s where things get disgusting. Memory latency is about 76% higher than on Lynnfield. That’s just abysmal. It’s also reflected in the memory bandwidth scores. While Lynnfield can manage over 15GB/s from its dual-channel memory controller, Clarkdale can’t break 10. Granted this is higher than the Core 2 platforms, but it’s not great.

What we’re looking at is a Nehalem-like CPU architecture coupled with a 45nm P45 chipset on-package. And it doesn’t look very good. If anything was going to hurt Clarkdale’s performance, it’d be memory latency.

Index Clarkdale: The Perfect Home Theater PC
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  • Jamahl - Monday, January 4, 2010 - link

    If this is a sign of things to come from intels 32nm, AMD must be laughing their asses off.

    Every one of these cpu's is an overpriced piece of garbage.
    Reply
  • ereavis - Monday, January 4, 2010 - link

    Phenom II X2 550 should be on this list, it's the direct competitor to the i3 -- dual core with real cache. It beats the Athlon II X4 processors and the Athlon II X2 don't even belong. Reply
  • ereavis - Monday, January 4, 2010 - link

    blasted no edit function. The 550 is also about the same price point.

    Guess I didn't combine criticism with the fact that this review was exactly what I've been waiting for and very well written, I like the added IGP page as I'm sitting on a 785 IGP while discrete cards are in between releases. All of which may get passed on to my mom's dying Sempron if an I3 deal pops up.

    Also minor correction, the Phenom II 925 is an X4. Where are the release dates?
    Reply
  • SilentSin - Monday, January 4, 2010 - link

    I second your question to Intel about the pricing of the 32nm i5 chips...who the hell is going to buy that? The i3's are looking pretty sweet as an alternative to an AMD HTPC platform at that low price point, though. March should make for an interesting competition once AMD launches their new RD890G (4350 based) chipsets. I'm guessing those will thoroughly trounce the GMA part on these chips as well as having quite a few features that the Intel HD stuff can't do, but at least Intel put something up that isn't completely laughable for once. Reply
  • Cogman - Monday, January 4, 2010 - link

    x264 is NOT a codec. Let me repeat that, x264 is NOT a codec. It is an ENCODER. The video output from x264 is in the H.264 standard (or codec if you like).

    Saying that x264 is an alternative to H.264 is retarded. It isn't an alternative, it USES the H.264 standard. Its like trying to say that mySQL is an alternative to the Ansi SQL standard. It isn't an alternative, it is an implementation of it.
    Reply
  • puffpio - Monday, January 4, 2010 - link

    hahaha..that always gets on my nerves too!
    but you can take it as a compliment that x264's popularity is strong enough that people mistake it for h264..

    people make the same mistake with divx, kleenex, qtip, xerox, etc...
    Reply
  • Anand Lal Shimpi - Monday, January 4, 2010 - link

    My apologies for sounding like a fool :-) I've updated the text. I just meant that it was an alternative to closed source H.264 encoders but my phrasing was absolutely horrendous for that purpose.

    Thanks for pointing out the error :)

    Take care,
    Anand
    Reply
  • proneax - Monday, January 4, 2010 - link

    I would like to see you measure the power consumption on the DH55TC using the integrated graphics.

    Legitreviews shows Idle/Load of 49/99W for the 661 in that setup.
    Reply
  • Anand Lal Shimpi - Monday, January 4, 2010 - link

    Agreed - I'll do it as soon as I'm back in the office. Just gotta survive CES :)

    Take care,
    Anand
    Reply
  • medi01 - Monday, January 4, 2010 - link

    Dual core 3.3Ghz CPU + Radeon 5870 consuming only 110 watt at load??? Reply

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